Size of the moving window. This is the number of observations used for
calculating the statistic. Each window will be a fixed size.

If its an offset then this will be the time period of each window. Each
window will be a variable sized based on the observations included in
the time-period. This is only valid for datetimelike indexes. This is
new in 0.19.0

min_periods : int, default None

Minimum number of observations in window required to have a value
(otherwise result is NA). For a window that is specified by an offset,
this will default to 1.

center : boolean, default False

Set the labels at the center of the window.

win_type : string, default None

Provide a window type. If None, all points are evenly weighted.
See the notes below for further information.

on : string, optional

For a DataFrame, column on which to calculate
the rolling window, rather than the index

closed : string, default None

Make the interval closed on the ‘right’, ‘left’, ‘both’ or
‘neither’ endpoints.
For offset-based windows, it defaults to ‘right’.
For fixed windows, defaults to ‘both’. Remaining cases not implemented
for fixed windows.